Just found this thread and my issue is related the the serpentine belt. As you can see from the photos the belt was rubbing against what looks to be the anti-sway bar. How can this be remedied before replacing the belt? Also the NAPA part # 25-050570 is the correct belt?
I'm not seeing any pictures, but when the motor mounts get old and worn, they can compress and allow the crankshaft pulley (that drives the AC belt) to move down and make contact with the black suspension rod that runs across underneath it, just aft of the radiator. I'm guessing that if your serpentine belt is touching the round rod that spans from side to side underneath it, your motor mounts need to be replaced.
'88 Quad - "Claudia"